Still though, it's hard to avoid getting condensation after stuff has been outside for a while - any more options?
If your scope allows, a small fan is never any harm. A low rpm fan just blowing air accross the objective lens or objective mirror, helps keep it a stable temperature. This limits the amount of expansion, keeps ita constant temperature, and prevents dew/condensation from settling on the surface.
Just that in winter, have a few spare batteries handy - they tend to die quicker, especially rechargeables, in extreme cold.
Seanie.
  